1. Field of the Invention
The present invention generally relates to the manufacture of semiconductor devices. More particularly, the present invention relates to an etchant for etching nitride and to a method for removing a nitride layer of a semiconductor device using the etchant.
A claim of priority under 35 USC § 119 is made to Korean Patent Application No. 2003-43306, filed on Jun. 30, 2003, the contents of which are herein incorporated by reference in their entirety for all purposes.
2. Description of the Related Art
The manufacture a semiconductor device typically includes a number of repeatedly performed processes of forming various layers and etching the layers to obtain desired patterns. Further, the layers or the patterns are often treated in some manner to realize certain material characteristics. These processes can adversely result in the generation of unwanted particles.
The particles may be generated from a semiconductor fabricating equipment, and from layers positioned on a backside and a bevel of a processed semiconductor substrate. As the particles generated from the layers positioned on the backside and the bevel of the semiconductor substrate have become more significant, an etchant for removing the layers has been studied.
As described above, processes for manufacturing a semiconductor device are repeatedly carried out. The actual substrate processed in a given process is treated for inspecting conditions of the substrate. For example, to inspect a thickness and a property of a layer formed on the actual substrate and a capacitance of a semiconductor device, the inspection process is performed on a dummy substrate that is loaded into a process line with the actual substrate.
After the inspection process is completed, a process for removing a layer that is formed on the dummy substrate is carried out on the dummy substrate. Then, the dummy substrate may be reused or discarded. Since the cost of the substrate has increased as the substrate size of the substrate exceeds 300 mm, the dummy substrate has been more often reused than discarded.
The removing process removes the layer on the substrate using an etchant. Accordingly, an etchant for etching the layer without damaging the substrate is in demand. To effectively remove the layer, the etchant is selected in accordance with material characteristics of the layer.
The layers formed on the backside and the bevel of the substrate may include polysilicon, nitride and oxide. Particularly, the layer may mainly include nitride. Unnecessary nitride remaining on the backside and the bevel of the substrate is removed using the etchant. The etchant for removing nitride varies in accordance with processes. For example, the etchant for removing nitride that is formed on the bevel of the substrate may include a phosphorous acid (H3PO4) solution. The etchant for removing the layer that is formed on the dummy substrate may include a hydrofluoric acid (HF) solution.
However, the time for removing nitride or the layer is so long so using the phosphorous acid solution and the hydrofluoric acid solution that these solutions are not desirable. Furthermore, atoms contained in the phosphorous acid solution or the hydrofluoric acid solution are chemically reacted with each other at a high temperature which can cause damage to the substrate. For example, the phosphorous acid solution removes nitride too slow at a relatively low temperature of about 160° C. The hydrofluoric acid solution removes the layer including nitride proportional to a temperature increase of the hydrofluoric acid solution. Fumes may be generated in the removal process using the hydrofluoric acid solution such that the semiconductor fabricating equipment may be damaged.
As above-mentioned, although nitride may be rapidly removed at a high temperature, the substrate may be thermally damaged due to the high temperature such that particles are generated from the damaged substrate. On the contrary, a time for removing nitride may be too long when the conventional etchant is used at a low temperature.